1. Field of the Invention
This invention relates to mass dampers for reducing undesirable vibration in automobiles having a unibody chassis. More particularly, the present invention provides a single mass damper capable of significantly reducing torsional vehicle vibration of the unibody chassis having a convertible roof.
2. Disclosure Information
It is well known in the automotive noise, vibration and harshness art to use mass dampers to reduce vibration of specific components attached to an automotive vehicle chassis. Generally, a mass damper is attached directly to the structure as near as possible to the specific component for which vibration reduction is desired. By resiliently mounting a predetermined mass directly to the identified vibrating structure and tuning the mass damper to the vibrating frequency of the specific component, the undesired vibration can be significantly reduced. However this approach is limited where there is insufficient package space to physically attach a mass damper adjacent to the specific component. Furthermore, this approach may require multiple mass dampers to reduce vibrations of more than one vibrating component.
As an alternative solution, a mass damper may be physically attached to or adjacent to a source of excitation, such as an internal combustion engine, having a predetermined idle speed and a corresponding frequency of vibration. A mass damper may be tuned to match the engine idle speed frequency and attached to or near the internal combustion engine. This approach reduces the vibration energy transferred to the vibrating structure, thereby reducing the overall vibration of the structure and the associated components. Following this approach, several mass dampers, may be required to reduce the vibrations caused by multiple excitation sources.
It would be desirable to have a single mass damper capable of absorbing vibration energy from a variety of excitation sources that is effective at reducing the vibration of the vibrating structure and specific components.